Vehicle suspension system

Abstract

A vehicle suspension system includes suspension arms mounted to a vehicle body frame to be pivotable between a low rolling posture and a high rolling posture and an anti-roll bar unit. The anti-roll bar unit includes a main anti-roll bar and a sub anti-roll bar. The sub anti-roll bar extends at least partially parallel with the main anti-roll bar. In the low rolling posture of the suspension arms, the main anti-roll bar and the sub anti-roll bar are not in contact with each other. In the high rolling posture of the suspension bars, the main anti-roll bar and the sub anti-roll bar are in contact with each other to increase stiffness of the anti-roll bar unit.

The invention claimed is: 
     
       1. A vehicle suspension system comprising:
 left and right suspension arms mounted to a vehicle body frame to be pivotable between a low rolling posture and a high rolling posture; and 
 an anti-roll bar unit that bridges the left suspension arm with the right suspension arm, the anti-roll bar unit including:
 a main anti-roll bar having a left end operably attached to the left suspension arm and a right end operably attached to the right suspension arm; and 
 a sub anti-roll bar extending at least partially parallel with the main anti-roll bar; 
 wherein in the low rolling posture, the main anti-roll bar and the sub anti-roll bar are not in contact with each other; and in the high rolling posture, the main anti-roll bar and the sub anti-roll bar are in contact with each other to increase stiffness of the anti-roll bar unit, and 
 wherein the main anti-roll bar and the sub anti-roll bar are pivotally supported to the vehicle body frame. 
 
 
     
     
       2. The vehicle suspension system of  claim 1 , wherein:
 the main anti-roll bar includes a main bar body which extends straight in the vehicle body transverse direction, a left main arm which is bent from the left end of the main bar body and extends rearwards in the vehicle body front/rear direction, a right main arm which is bent from the right end of the main bar body and extends rearwards in the vehicle body front/rear direction, a left link having one end connected to the left main arm and the other end connected to the left suspension arm and a right link having one end connected to the right main arm and the other end connected to the right suspension arm; and 
 the sub anti-roll bar includes a sub bar body extending straight in the vehicle body transverse direction, a left sub arm which is bent from the left end of the sub bar body and extends rearwards in the vehicle body front/rear direction and a right sub bar arm which is bent from the right end of the sub bar body and extends rearwards in the vehicle body front/rear direction. 
 
     
     
       3. The vehicle suspension system of  claim 2 , wherein:
 the leading end region of the left sub arm is formed as a left ring through which the left main arm extends, an inner circumferential wall of the left ring coming into contact with the left main arm in the high rolling posture; and 
 the leading end region of the right sub arm is formed as a right ring through which the right main arm extends, an inner circumferential wall of the right ring coming into contact with the right main arm in the high rolling posture. 
 
     
     
       4. The vehicle suspension system of  claim 3 , wherein:
 the inner circumferential walls of the left ring and the right ring respectively come into contact with the left main arm and the right main arm via an elastic member. 
 
     
     
       5. The vehicle suspension system of  claim 2 , wherein:
 the main bar body and the sub bar body respectively are attached to the vehicle body frame via a bush. 
 
     
     
       6. A vehicle suspension system comprising:
 left and right suspension arms mounted to a vehicle body frame to be pivotable between a low rolling posture and a high rolling posture; and 
 an anti-roll bar unit that bridges the left suspension arm with the right suspension arm, the anti-roll bar unit including: 
 a main anti-roll bar having a left end operably attached to the left suspension arm and a right end operably attached to the right suspension arm; and 
 a sub anti-roll bar extending at least partially parallel with the main anti-roll bar; 
 wherein in the low rolling posture, the main anti-roll bar and the sub anti-roll bar are not in contact with each other; and in the high rolling posture, the main anti-roll bar and the sub anti-roll bar are in contact with each other to increase stiffness of the anti-roll bar unit, 
 wherein the main anti-roll bar and the sub anti-roll bar are mounted independently of each other, and 
 wherein ends of the sub anti-roll bar encircle ends of the main anti-roll bar and the encircled ends of the sub anti-roll bar are not in contact with the main anti-roll bar in the low rolling posture but are in contact with the main anti-roll bar in the high rolling posture. 
 
     
     
       7. A vehicle suspension system comprising:
 left and right suspension arms mounted to a vehicle body frame to be pivotable between a low rolling posture and a high rolling posture; and 
 an anti-roll bar unit that bridges the left suspension arm with the right suspension arm, the anti-roll bar unit including: 
 a main anti-roll bar having a left end operably attached to the left suspension arm and a right end operably attached to the right suspension arm; and 
 a sub anti-roll bar extending at least partially parallel with the main anti-roll bar; 
 wherein in the low rolling posture, the main anti-roll bar and the sub anti-roll bar are not in contact with each other; and in the high rolling posture, the main anti-roll bar and the sub anti-roll bar are in contact with each other to increase stiffness of the anti-roll bar unit, 
 wherein the main anti-roll bar and the sub anti-roll bar are mounted independently of each other, and 
 wherein elongated portions of the main anti-roll bar and the sub anti-roll bar extend parallel to one another and are vertically aligned when mounted.